Research On Energy-Saving Control Method Of Belt Conveyors In Bulk Terminal

Recently,with the rapid increasing cargo throughput in China,energy waste problems caused by the energy-consuming and low efficiency equipment have become increasingly serious.Belt conveyors,as the most critical equipment for transporting bulk material,have advantages of long distance,high speed and large capacity compared with other means.However,due to their maximum configuration of drive power and constant speed operation whenever no load or lightly load,belt conveyors consume a considerable proportion of the total power supply during the material handling process.What is more,it wastes more electricity energy because of installed capacities of belt conveyors meet or exceed the total energy consumption for real demand.Therefore,it is a necessary way to accelerate the establishment of energy saving,high efficiency,intensive green terminal by accelerating intelligence reconstruction of belt conveyors and improving their energy efficiency.A belt conveyor system can work effectively when the motor torque characteristics matchs well its load characteristic.As a result,the technique of adaptive speed control based on real-time load has been one of key research emphasis and difficulty of intelligent control.However,there are still a number of problems about insufficient precision of material flow rate and low control security to be solved.In order to tackle this challenge,this dissertation researches on the energy consumption law of a belt conveyor and its influential factors,bulk material flow measurement based on laser scanning technology,dynamics modeling considering the actual load,speed control and simulation.It will contribute to improving the speed regulation control security and scientific level of a belt conveyor.The research work major the following parts:Firstly,the energy consumption law of a belt conveyor and its main influencing factors are researched.On the basis of the accepted design criteria,we deduce two categories of models for calculating belt conveyor's energy consumption.Moreover,the influence factors of the energy consumption are determined.These factors include structural parameters,operation parameters or others,which operation parameters are the main factors.Base on theoretical analysis,a test apparatus for measuring the energy consumption of belt conveyor is designed and developed.After determining the test scheme and test parameters,the energy consumption law and the main influence factors are revealed basically through the experiment research of this test apparatus under different working condition.Also,the limits on the accuracy of current energy consumption measuring model is analysed.Secondly,the research on bulk material flow measurement of a belt conveyor based on laser scanning technology is carried out.According to the principles of bulk material dynamic measurement and laser measurement system,a contour acquisition method of bulk material flow based on laser scanning is presented.After the space-time data of material flow profile are obtained by coordinate transformation,the spatial form characteristics of the material flow cross-section contour are analyzed.Then the cross sectional area can be calculated by accumulating the triangle area or trapezoidal area when material flow cross-section contour automatic has been extracted.Thus,the bulk material flow can be calculated based on the area integral.Finally,we develop the bulk material flow measurement system based on laser scanning technology and verify the accuracy and reliability of this system.Third,a belt conveyor dynamics model is built with the actual load distribution take into consideration.The bulk material flow data are used to establish a mechanic model of loaded belt.Then,taking longitudinal characteristics as the analysis object,this dissertation establishes the longitudinal dynamic model of a belt conveyor considering the actual load and confirms model parameters.Finally,the simulations for dynamic characteristics law under actual load distribution are accomplished by established a discrete element simulation model of a belt conveyor and a soft start control model based on Matlab.The simulation result could provide the basis for determining speed control strategy of a belt conveyor.Finally,the speed control strategy for energy efficiency improvement of a belt conveyor is proposed.First we set the optimization goal and system constraints.Then,an energy consumption prediction model of a belt conveyor based on RBF neural network is built based on real data.To meet the requirements of control performance,a self-tuning controller based on fuzzy PID is designed,which can realize PID parameters online self-tuning.The simulations for adaptive control by fuzzy PID parameters self-tuning are accomplished.After that,we design and build a speed control simulation system of a belt conveyor.Then,simulation tests for the speed control of the simulation system are carried out,which can examine the control effect of the proposed control methods on the simulation system preliminarily.The proposed control methods could lay the theoretical and technical foundation for multi-level belt conveyors coordination control.